Conventionally, deposits are formed on workpieces (e.g., substrates) prior to mounting components by jetting droplets of viscous medium (e.g., solder paste, glue, etc.) onto the workpiece. A conventional jetting system generally includes a nozzle space for containing a relatively small volume of viscous medium prior to jetting, a jetting nozzle coupled to the nozzle space, an impacting device for impacting and jetting the viscous medium from the nozzle space through the jetting nozzle in the form of droplets, and a feeder for feeding the medium into the nozzle space.
Since production speed is a relatively important factor in the manufacturing of electronic circuit boards, the application of viscous medium is typically performed “on the fly” (i.e., without stopping for each location on the workpiece where viscous medium is to be deposited).
A conventional method for depositing viscous medium past an edge surface of a workpiece includes capillary needle dispensing together with optical systems that identify the pad where the dispensed material will be applied. This conventional method of capillary needle dispensing has certain limitations, including limitations in dispensing speed and sensitivity. The dispensing speed is limited because the dispensing system must stop for each location on the substrate to make contact with the position on the workpiece where a certain amount of viscous medium is to be deposited. The sensitivity to surface topology is limited due to the relatively small dispensing distance of the dispensing head.